Alcohol use, abuse, and dependence are prevalent among HIV-infected individuals, and are associated with delayed initiation of and adherence to antiretroviral therapy (ART), and with HIV disease transmission and progression. Prior research on the intersection of alcohol and HIV has been conducted in relatively small samples or in select groups whose results may not be generalizable to the overall population of HIV-infected individuals. The Alcohol Research Consortium in HIV - Epidemiology Research Arm (ARCH-ERA), will address this deficit in our knowledge by studying the short and long-term effects of alcohol on clinical outcomes among persons with HIV. We will accomplish this by elucidating the burden of alcohol use, its effect on HIV disease progression, and its impact on engagement in clinical care, health care utilization and costs. ARCH-ERA will be based in the CFAR Network of Integrated Clinical Systems (CNICS), a national network of 8 HIV clinical care sites and over 20,000 HIV-infected men and women receiving HIV care. CNICS is the ideal setting for ARCH-ERA because of its collection of comprehensive patient care and clinical outcomes data that is linked to patient-provided information on alcohol use, substance use, medical and psychiatric morbidities, adherence, HIV transmission risk behaviors, and quality of life (QOL). Capitalizing on the resources and infrastructure of CNICS, we propose the following aims: To determine the burden of hazardous alcohol consumption to HIV infected individuals; to determine the impact of different levels and pattern of alcohol use on HIV disease progression over time, and to evaluate the impact of alcohol use on HIV health care utilization and costs of care. Particular attention will be paid to the roles of sex/gender, illicit drug use, and mental health symptoms in the relationship between alcohol and HIV.